/*
 * Copyright (c) 2020 - present, Inspur Genersoft Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License. 
 */

package io.iec.edp.caf.multicontext.support;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.RuntimeBeanReference;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.boot.type.classreading.ConcurrentReferenceCachingMetadataReaderFactory;
import org.springframework.context.ApplicationListener;
import org.springframework.context.annotation.AnnotationConfigUtils;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.core.Ordered;
import org.springframework.core.PriorityOrdered;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReaderFactory;

//todo 建立metadata缓存 和主metadataReader共享

/**
 * 此类用于向各模块的容器内注册Bean：SharedMetadataReaderFactoryBean，最终是用于读取模块内的spring.factories
 * 读取spring.factories的FactoryLoader应该是从这个bean上拿到的ResourceLoader，进而进行读取
 */
public class ModuleMetadataReaderFactoryPostProcessor implements BeanDefinitionRegistryPostProcessor, PriorityOrdered {
    public static final String BEAN_NAME = "org.springframework.boot.autoconfigure."
            + "internalCachingMetadataReaderFactory";

    @Override
    public int getOrder() {
        // Must happen before the ConfigurationClassPostProcessor is created
        return Ordered.HIGHEST_PRECEDENCE;
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
    }

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        register(registry);
        configureConfigurationClassPostProcessor(registry);
    }

    private void register(BeanDefinitionRegistry registry) {
        BeanDefinition definition = BeanDefinitionBuilder
                .genericBeanDefinition(SharedMetadataReaderFactoryBean.class, SharedMetadataReaderFactoryBean::new)
                .getBeanDefinition();
        registry.registerBeanDefinition(BEAN_NAME, definition);
    }

    private void configureConfigurationClassPostProcessor(BeanDefinitionRegistry registry) {
        try {
            BeanDefinition definition = registry
                    .getBeanDefinition(AnnotationConfigUtils.CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME);
            definition.getPropertyValues().add("metadataReaderFactory", new RuntimeBeanReference(BEAN_NAME));
        } catch (NoSuchBeanDefinitionException ex) {
        }
    }

    /**
     * {@link FactoryBean} to create the shared {@link MetadataReaderFactory}.
     */
    static class SharedMetadataReaderFactoryBean
            implements FactoryBean<ConcurrentReferenceCachingMetadataReaderFactory>, BeanClassLoaderAware,
            ApplicationListener<ContextRefreshedEvent> {

        private ConcurrentReferenceCachingMetadataReaderFactory metadataReaderFactory;

        @Override
        public void setBeanClassLoader(ClassLoader classLoader) {
            this.metadataReaderFactory = new ConcurrentReferenceCachingMetadataReaderFactory(classLoader);
        }

        @Override
        public ConcurrentReferenceCachingMetadataReaderFactory getObject() throws Exception {
            return this.metadataReaderFactory;
        }

        @Override
        public Class<?> getObjectType() {
            return CachingMetadataReaderFactory.class;
        }

        @Override
        public boolean isSingleton() {
            return true;
        }

        @Override
        public void onApplicationEvent(ContextRefreshedEvent event) {
            this.metadataReaderFactory.clearCache();
        }

    }
}
